| Author |
Message |
    
flipper (Unregistered Guest)
Unregistered guest
| | Posted on Friday, October 15, 2004 - 12:22 pm: | 
|
its mounted on the tool box in the bed and cant get the swr below 2.3...and dont want to cut any more off the whip any ideas will help. |
Viking
Intermediate Member
Username: Viking
Post Number: 163
Registered: 2-2002
| | Posted on Friday, October 15, 2004 - 3:43 pm: |
|
Did you really cut some off? I've always ended up adding the 4" spring and have it be fine. IS the center lead isolated from ground? |
Lazylizard
Junior Member
Username: Lazylizard
Post Number: 27
Registered: 2-2004
| | Posted on Friday, October 15, 2004 - 3:54 pm: |
|
We need more info:
1. How is it grounded?
2. What type of mount?
3. Is the bed grounded to the frame?
4. What type of radio (and box if ya got it)?
5. Coax type and routing.
Let us know. |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Friday, October 15, 2004 - 7:37 pm: |
|
Viking is absolutely right....
You need to add the heavy duty spring to a 102 whip for CB band freqs. Take the spring off for the 10 meter ham band.
If you had to cut the whip then your SWR was probably a little over 3 to begin with which means you definately have a bad ground. Your tool box (I hope it is a metal box) is not grounded to the chassis of your truck. SCRAPE the paint off a small area of the box of the truck (out of sight behind the box) and buff with sandpaper a small section of the tool box. Using a grounding strap aka a shield from a RG8 coax ground connect the two via the braid to the bare metals. AND while you are at it, make another grounding strap and physically bond via the grounding strap the box to the chassis of the truck as well.
Point 2...
Get and use the heavy duty spring.
Point 3...
replace the whip if you cut it. IF you did not cut it too severly you can splice it back using a split nut from a hardware store but the repar will look hmmm not pretty. Best to just grit and buy a new one.
Point 4...
IF replacing get a Stainless Steel whip as it can bend but will not break as fiberglass whips are prone to do from time to time.
|
1861
New member
Username: 1861
Post Number: 8
Registered: 2-2004
| | Posted on Saturday, October 16, 2004 - 1:10 pm: |
|
I TRIED THE 4 SPRING ON MINE , STILL COULDN,T GET SWR DOWN WHERE I WANTED , REPLACED IT WITH A 7 INCH ALL THREAD SS BOLT , SWR FLAT AND LESS FLOP ON ANTENNA |
flipper (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, October 16, 2004 - 3:13 pm: |
|
yea its a metal box with a good ground with a regular mirror mount bolted to it.
and i allways have good service out of steel whips without the spring just most of the time have to cut about a 1/4in off the top.
its a cobra 148, with a messanger2v amp. swr is still high with out the box in line also. and i even tried another radio and box and got the same reading. |
Allagator
Intermediate Member
Username: Allagator
Post Number: 480
Registered: 9-2002
| | Posted on Saturday, October 16, 2004 - 3:50 pm: |
|
add a 4 inch spring and check it again ive only had one 102" whip i have never had to add a spring and it was homemade 108" so i never had to do anything !!! but i would try a 4" spring !!
but it is just my 2 cents !!!
Allagator !!
|
flipper (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, October 16, 2004 - 4:07 pm: |
|
i've tried a spring and every thing but still nothing. wrapped some copper wird around the center of the anttenna and got swr down to 1.3..
i can slide the wire up or down and it goes right back up to a 2+...
so i am going to try another center loaded anttenna and see what happens |
Allagator
Intermediate Member
Username: Allagator
Post Number: 481
Registered: 9-2002
| | Posted on Saturday, October 16, 2004 - 6:40 pm: |
|
i would try some NEW COAX for the next step !!!!
and double check the ground on the antenna mount cause if its mounted on a tool box a ground wire would be needed to make a propper ground !!!
but i tried my best to help !!!
Allagator |
flipper (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, October 17, 2004 - 1:46 pm: |
|
its got a great ground,, cause i can take the ground wire off the amp and leave the hot on the batt and it will still come on(but thats not how i run the amp and radio) tried another anttenna and it works great guess i just got a lemmon with that 102" whip that time |
Carolinagold
Junior Member
Username: Carolinagold
Post Number: 25
Registered: 12-2002
| | Posted on Sunday, October 17, 2004 - 5:06 pm: |
|
i got flippers antenna working now had a bad coax end on it got the whip working great. thanks for the input yall |
Alsworld
Advanced Member
Username: Alsworld
Post Number: 878
Registered: 1-2002
| | Posted on Sunday, October 17, 2004 - 11:06 pm: |
|
Nice find CarolinaGold! Sometimes those can be difficult to locate.
My friend just brought home a motorhome yesterday (used) that the CB would not receive. Easy to troubleshoot but I don't have time to fix prior to me leaving overseas. The antenna is now off and he won't use it until I get back home and set him up well. It will have to be a typical fiberglass motorhome no-ground antenna, but I can do a much better job than those who originally set it up.
Not a bad deal though, he's got a Cobra 25 in there. He is not a big CB'er, just wants to talk to those that are close to him. I'll do him right.
Alsworld |
Carolinagold
Junior Member
Username: Carolinagold
Post Number: 26
Registered: 12-2002
| | Posted on Monday, October 18, 2004 - 1:55 pm: |
|
well to tell the truth it was really just dumb luck i started taking the coax off and when i started to unscrew it i got all kinds of recive (was real weak before)but it wasnt grounded out to the shield just a bad connection. but i put a 3" tall threaded rod connector on it and the swr is 1.3 with the box off and 1.5 with box on and in high gear. so i guess he's happy with it now |
865
New member
Username: 865
Post Number: 1
Registered: 10-2004
| | Posted on Monday, October 18, 2004 - 2:37 pm: |
|
yea carolinagold got my 102 whip working pretty well. i couldnt figure it out. but i did get some great ideas from you folks. thanks for all the help |
Tech808
Moderator
Username: Tech808
Post Number: 3858
Registered: 8-2002
| | Posted on Monday, October 18, 2004 - 3:21 pm: |
|
865,
WELCOME TO THE COPPER FORUM!
Have you read about our CEF Radio Club Yet?
Sure would enjoy adding you to our CEF Membership list!
Lon
Tech808 |
icmn_cook (Unregistered Guest)
Unregistered guest
| | Posted on Friday, December 10, 2004 - 8:50 pm: |
|
i run a 102 whip on my pic up with a 4inch spring and it gets great recieve. I was running fire sticks until i changed, will not go back. |
Coyote
Junior Member
Username: Coyote
Post Number: 17
Registered: 11-2004
| | Posted on Saturday, December 11, 2004 - 11:56 am: |
|
I use a 102" with no spring and have talked from Alberta Canada to everywhere on the West Coast. Would adding a spring make any differnce? My only "real" problem is getting lots of different electronic interference from the vehicle. The windshield wipers, turn signals, when i hit the brake pedal(brake lights)and i think its the sensor for the speedometer that is the constant one always interfering but no ignition interference. btw... its a chevy S-10 its mounted to. I can disconnect the coax from the antenna base and the noises stop. Bad ground on the antenna? yes... its mounted to a metal tool box that is grounded both ways. maybe i need to redo the connections since its been about a year since it was installed. But i've always had this problem. any suggestions? |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, December 11, 2004 - 10:22 pm: |
|
Coyote - The antenna shouldn't be grounded, the shield of coax should. Most antenna mounts accomplish this for you - how would depend on the particular mount you've used for your antenna. My guess is that everything is fine if it seems to be working normally and you have good range.
What you are experiencing is RFI from electronic or electrical devices on your vehicle. They aren't comming through the radio's ground because when you disconnect the antenna they go away. They are actually being received by the antenna.
There are a large number of ways to combat noise from a vehicle. I've used a combination of bypass capacitors and chokes to kill enough noise on my cars that I don't need to use the radio's noise blanker or automatic noise limiter unless I'm in traffic. I can actually tell when a passing car has high performance spark plugs and I can hear other car's windshild wipers!
The most important part of eliminating noise is to do it at the source so there is less of a chance of it radiating. For windshild wiper noise or any other small electrical engine noise (fans, fuel pumps, etc.) I suggest using a feed through filter capacitor in the power line if you can find one, or a small electrolytic capacitor to simply bypass the RFI to ground. The feed through filter capcitor does the same thing as the small bypass capacitor, but it's very sturdy and I've never had one fail. I've actually moved them from one car to another and they still work fine. The closer you can put the capacitor to the actual device the better the noise will be eliminated.
Good luck! |
Poppathree
Junior Member
Username: Poppathree
Post Number: 24
Registered: 2-2004
| | Posted on Saturday, December 11, 2004 - 11:41 pm: |
|
Racer x, Are those the small "rf chokes" that rat shack sells for phones, etc?? The ones that just snap over the wire? Or something else....if so where can I get them because I have lots of rf noise as well, Lee |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, December 12, 2004 - 5:09 am: |
|
Bypass capacitors are your best measure for supression of electrical engine noise.
RF snap on chokes aren't really good for anything except sensor signal wires, and I really doubt that you're getting much interference from sensors as they usually relay DC voltage as information.
Rat Shack used to sell what they called a feed-through filter capacitor which was excellent in combating electrical noise. It could be inserted in the positive lead of any engine and could handle loads of up to 40 amps, although I never used them at anywhere near that load. Check and see if you can find some of them. The last one I bought years ago was $5.99.
If you can't buy them anymore you can always just use an axial lead electrolytic capacitor with a value of about 1/2 picofarad or more. Connect the anode (positive lead) to the point where the positive lead feeds the windshield wiper engine, and then connect the cathode (negative lead) to the nearest ground point. Keep the leads as short as possible and you should totally eliminate any noise comming from the engine. |
Coyote
Junior Member
Username: Coyote
Post Number: 18
Registered: 11-2004
| | Posted on Sunday, December 12, 2004 - 9:58 am: |
|
Thanks Racer X, I'll see if I can track some of these capacitor's down.
On another note, why don't you register Racer X? You seem very knowledgeable about radio's and we can always use another knowledgeable person in the rest of the forum's. Its free  ...
....who was that masked man?
73 and thanks again
CEF443 |
beaker (Unregistered Guest)
Unregistered guest
| | Posted on Monday, December 13, 2004 - 1:20 am: |
|
Um Flipper.....Question, How long is your coax you are using with your whip antenna? Reason I'm asking is because that's what I use as well, One thing I've found to be true about these whips is.....Unless you have "ample" coax length you won't get a good swr reading. Mine I had to have 22 ft. of coax. |
Starface
New member
Username: Starface
Post Number: 8
Registered: 1-2005
| | Posted on Tuesday, January 18, 2005 - 7:50 pm: |
|
If you are experiencing SWR that is high across the entire band and have eliminated shorts, opens, groundless mounts and coax as potential problems, suspect lack of ground plane. Try adding a spring or quick disconnect to the antenna base. In some cases, the repositioning of the antenna relevant to available ground plane will solve the problem.
|
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 147
Registered: 12-2003
| | Posted on Wednesday, January 19, 2005 - 7:25 pm: |
|
icmn cook,
How is your whip mounted on your pick up? I'm just wondering because I have a pick up also and a 102" whip that I'm not using right now. Maybe I'll mount it on my truck and see what happens. |
